Symptomatic calcification of a thyroid lobe and surrounding tissue after radioactive iodine treatment to ablate the lobe.

BACKGROUND

Fine-needle aspiration diagnosis of follicular carcinoma presents a dilemma because malignancy is confirmed when vascular or capsular invasion is present. Completion thyroidectomy may be necessary when the diagnosis of follicular carcinoma is made following hemithyroidectomy. Ablation of the remaining lobe with radioactive iodine has been used as an alternative to completion thyroidectomy. Here we report an unusual apparent complication of this treatment.

PATIENT FINDINGS

A 51-year-old woman presented in September 24, 2009 with a stony, hard calcification of left thyroid gland. She complained of recent progressive hoarsening of her voice. Her medical history was positive for a subtotal thyroidectomy on September 6, 1993. Histologic analysis identified follicular carcinoma. Two months postoperatively, the remaining tissue was ablated with (131)I (150 mCi) as an alternative to completion thyroidectomy. We performed computed tomography of the neck, which demonstrated 1.6  x 1.9 x  2.2 cm dense speculated calcification of the entire left residual thyroid gland. The calcification infiltrated the trachea wall. Completion thyroidectomy, including resection of the calcification, was performed. Histologic examination revealed dystrophic calcification.

CONCLUSION

We report an unusual replacement of the thyroid remnant with calcification that developed over a period of 16 years following radioactive iodine lobe ablation as an alternative to completion thyroidectomy for thyroid follicular carcinoma. To our knowledge, this is the first such case in the English language literature.